A wide variety of machines, such as, but not limited to, construction machines and/or earthmoving machines (e.g., excavators, mining shovels, loaders, earth movers, bulldozers, front end loaders, motor graders, and the like), automobiles, aircraft, locomotives, and industrial pumping machinery, among other things, may utilize a plurality of actuators for positioning one or more components thereof, relative to another machine component and/or a worksite. Actuators for a machine may be associated with, or integrated within, any mechanical, electrical, and/or computer-based control systems, methods, and/or apparatus configured for controlling the machine in any manual, semi-autonomous, and/or autonomous control schemes.
Amongst a variety of actuators that may be used with machines, linear actuators are commonly used for positioning scenarios in which a machine, alone or in combination with other components, can be properly positioned via actuation in a single direction. This type of actuation is performed, generally, in a substantially straight-line path. To that end, a wide variety of linear actuators are available, utilizing a variety of mechanical and/or electromechanical inputs and/or components for performing actuation. Example linear actuators include, but are not limited to including, mechanical actuators, electro-mechanical actuators, pneumatic actuators, piezoelectric actuators, and hydraulic actuators.
In the case of heavy machinery, hydraulic actuators are commonly used for positioning heavy machine components, relative to one another and/or a worksite. Hydraulic actuators can be useful in such heavy machinery scenarios, by providing machine-universal control over such actuators, to a precise degree, via a series of control systems, pipes, pumps, and mechanisms, which communicate hydraulic fluid amongst the actuators, during operation. Due to the near-incompressible nature of most hydraulic fluids used in these systems, hydraulic actuators can be quite useful for moving heavy components of machines, with precision.
However, maintenance of hydraulic actuators and/or the associated control systems, piping and/or tubing, pumps, and mechanisms adds mechanical complexity to machines. In machines, greater mechanical complexity can lead to increased risk for component and/or system failure. Furthermore, hydraulic fluid levels and/or characteristics require regular attention, which introduces a need for increased operator and/or maintenance attention to the hydraulic system. While needs for increased attention can be replaced with currently known electronic systems and methods for monitoring hydraulic systems, these systems add further complexity to the machines, leading to more components that may be susceptible to part wear or failure.
Therefore, as an alternative to hydraulic actuators or for use in addition with hydraulic actuators, modern machines may utilize one or more electric linear actuators, which that can be configured to perform similar actuation mechanics as commonly used hydraulic actuators. An electric linear actuator utilizes one or more electric motors to generate torque. The generated torque is then converted, via one or more mechanisms of the electric linear actuator, into translational motion in a substantially straight-line path. For example, some prior art electric linear actuators have utilized external or internal motors that drive a long screw, which drives an actuator rod, within a housing or piston of the actuator. The length of the screw and/or the positioning of the motor, internal or external to the electric linear actuator, can limit the range of motion of an actuator rod, by not allowing maximum retraction of the rod within the housing.
To reduce a screw or internal size of an actuator rod, some electric actuators, such as the electric actuator disclosed in U.S. Patent Publication No. 2009/0044645, utilize a threaded spindle and an associated threaded nut, which moves translationally about the spindle and within a housing of the actuator. The electric motor of the actuator of the '645 publication drives rotational motion of the threaded spindle, which, in turn, causes the corresponding threaded nut to move translatory, within the housing, about the spindle. The translatory linear motion of the nut results in translatory linear actuation of the actuator rod of the actuator.
The threaded spindle, in the '645 publication, is rotationally driven by the electric motor and, therefore, requires connection to said motor. The spindle is, thus, connected to the motor, internal to the actuator body. Accordingly, the electric motor occupies a significant amount of space, within the actuator housing, that could otherwise be used for further retraction of the actuator rod. To that end, the range of motion of the actuator in the '645 publication may be limited, due to the placement of the motor, within the actuator housing.
In designing and/or producing electric linear actuators that are capable of being utilized to replace prior forms of actuators, it is desired that such actuators operate with the great degrees of mechanical simplicity for minimizing part failure, of operational efficiency for limiting cost of usage, and/or of spatial conservation for allowing greater range of motion with lessened mechanical and/or operational complexities. Therefore, electric actuators, for machines, which utilize innovative, compact component design and simplified operational characteristics, are desired.